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Volume 59 
Part 1 
Pages m29-m32  
January 2003  

Received 13 November 2002
Accepted 13 December 2002
Online 24 December 2002


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© International Union of Crystallography 2003

Key indicators
Single-crystal X-ray study
T = 153 K
Mean [sigma](C-C) = 0.007 Å
R = 0.050
wR = 0.094
Data-to-parameter ratio = 16.7
Details

Anhydrous tris(dibenzoylmethanido)(o-phenanthroline)europium(III), [Eu(DBM)3(Phen)]

Moawia O. Ahmed,a Jin-Long Liao,b Xiwen Chen,b Show-An Chenb* and John H. Kaldisc

aDepartment of Chemistry, National Taiwan University, 106 Taipei, Taiwan, Republic of China,bDepartment of Chemical Engineering, National Tsing-Hua University, Hsinchu, 30013 Taiwan, Republic of China, and cDepartment of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
Correspondence e-mail: sachen@chenthu.edu.tw

The hydrated tris(dibenzoylmethanido)(o-phenanthroline)europium(III) complex, [Eu(DBM)3(Phen)]·xH2O, is converted efficiently into anhydrous tris(dibenzoylmethanido)(o-phenanthroline)europium(III), [Eu(DBM)3(Phen)] or [Eu(C15H11O2)3(C12H8N2)], by heating under vacuum. The title compound has been characterized by FT-IR, 1H and 13C NMR spectroscopy, and X-ray diffraction methods. It crystallizes in the triclinic space group P[\overline 1] with five molecules in the asymmetric unit, without any pseudosymmetry. The trivalent europium ion is eight-coordinate, and the coordination polyhedron can best be described as a slightly distorted square antiprism.

Comment

There is much interest in the preparation of anhydrous europium [beta]-diketonate complexes. These complexes have been extensively studied with respect to applications as NMR shift reagents (Briggs, 1970[Briggs, J. (1970). Chem. Commun. pp. 749-750.]; Hinckley, 1969[Hinckley, C. C. (1969). J. Am. Chem. Soc. 91, 5160-5162.]) and as laser materials (Whan & Crosby, 1962[Whan, R. E. & Crosby, G. A. (1962). J. Mol. Spectrosc. 8, 315-327.]; Balzani, 1992[Balzani, V. (1992). Tetrahedron, 48, 10443-10514.]; Qian et al., 1997[Qian, D. J, Yang, K. Z, Nakahara, H. & Fukuda, K. (1997). Langmuir, 13, 5925-5932.]). More recently, lanthanides have attracted considerable attention for light-emitting diodes, because their photoluminescences (PL) exhibit high quantum efficiencies and very sharp spectral bands (Kido et al., 1994[Kido, J., Hayase, H., Hongawa, K., Nagai, K. & Okuyama, K. (1994). Appl. Phys Lett. 65, 2124-2126.]; Sano et al., 1995[Sano, T., Fujita, M., Fujii, T., Hamada, Y., Shibat, K. A. & Kuroki, K. (1995). Jpn. J. Appl. Phys. 34, 1883-1886.]; Edwards et al., 1997[Edwards, A., Claude, C., Sokolik, I., Chu, T. Y., Okamoto, Y. & Dorsinvill, R. (1997). J. Appl. Phys. 82, 1841-1846.]). Europium [beta]-diketonate complexes have been well established in the literature for many years (Whan & Crosby, 1962[Whan, R. E. & Crosby, G. A. (1962). J. Mol. Spectrosc. 8, 315-327.]; Pope et al., 1961[Pope, G. W., Steinbach, J. F. & Wagner, W. F. (1961). J. Inorg. Nucl. Chem. 20, 304-313.]; Halverson et al., 1964[Halverson, F., Brinen, J. S. R. & Leto, J. (1964). J. Chem. Phys. 40, 2790-2792.]; Mazdiyasni et al., 1966[Mazdiyasni, K. S., Lynch, C. T. & Smith, J. S. (1966). Inorg. Chem. 3, 342-346.]). Melby and co-workers have prepared a series of rare earth complexes and recorded their emission spectra (Melby et al., 1964[Melby, L. R., Rose, N. J., Abramson, E. & Caris, J. C. (1964). J. Am. Chem. Soc. 86, 5117-5125.]). However, most of these complexes are hydrated and contain inner coordinated water molecules, because their synthetic routes have generally used water-soluble salts, e.g. the hydrated tris(dibenzoylmethanido)(o-phenanthroline)europium(III), [Eu(DBM)3(Phen)], has been prepared by using EuCl3·6H2O. To the best of our knowledge, there were no published structural data or NMR studies of the anhydrous tris(dibenzoylmethanido)(o-phenanthroline)europium(III) complex. We report herein the solid-state structure of water-free [Eu(DBM)3(Phen)], (I[link]).

[Scheme 1]

The structural features of complex (I[link]) were identified on the basis of IR, and 1H and 13C NMR spectroscopy. The most notable feature in the IR spectrum of (I[link]) is the absence of O-H stretching vibrations, indicating that there are no inner coordinated water molecules in the complex, which is in good agreement with the results of the elemental analysis and crystal structure. A well resolved 1H NMR spectrum was observed for complex (I[link]). The spectrum shows a single peak at [delta] 16.89 p.p.m. for the enolic proton of the dibenzoylmethane ligand, four single resonances at [delta] 8.92, 10.01, 10.52 and 10.92 p.p.m. corresponding to the phenanthroline protons, and a multiplet at [delta] 6.59-8.00 p.p.m. for the phenyl protons.

The absorption and PL spectra of complex (I[link]), in a film formed by spin-coating directly on a quartz glass substrate (the spin-coating solution was 0.5wt% in chloroform), and in a THF solution at room temperature are shown in Fig. 1[link]. Complex (I[link]) has absorption and PL spectra nearly identical to the reported hydrated complex [Eu(DBM)3(Phen)]·xH2O (Melby et al., 1964[Melby, L. R., Rose, N. J., Abramson, E. & Caris, J. C. (1964). J. Am. Chem. Soc. 86, 5117-5125.]). The complex exhibits an absorption peak at 356 nm, which can be assigned to the allowed [pi]-[pi]* transition of the [beta]-diketone (DBM) ligand (Uekawa et al., 1998[Uekawa, M., Miyamoto, Y., Ikeda, H., Kaifu, K. & Nakaya, T. (1998). Bull. Chem. Soc. Jpn, 71, 2253-2258.]). It can be seen that the PL spectra (excitation wavelength 356 nm) of the film and solution are very similar. They both exhibit four sharp emission peaks at 579, 591, 612 and 653 nm corresponding to the 5D0[\rightarrow]7Fj (j = 0-3) transitions of the trivalent europium ion, respectively, in which the first, second and fourth peaks are weak and the third is the main peak. These emissions are a result of highly efficient intramolecular energy transfer from the ligand triplet state (which is generated by intersystem crossing from the singlet state of the ligand) to the excited state of the Eu3+ ion, 5D0, which then relaxes to the 7Fj (j = 0-3) states (Crosby & Whan, 1960[Crosby, G. A. & Whan, R. E. (1960). J. Chem. Phys. 32, 614-615.]; Bhaumik, 1965[Bhaumik, M. (1965). J. Chem. Phys. 42, 787-788.]).

The title compound, (I[link]), crystallizes in the space group P[\overline 1] with five crystallographically unrelated molecules in the asymmetric unit (Fig. 2[link]). No pseudosymmetry is observed among the five molecules. The structure for one of the five crystallographically independent molecules is depicted in Fig. 3[link]. The trivalent europium ion is eight-coordinate, and the coordination polyhedron can best be described as a slightly distorted square antiprism. The average Eu-O bond distances in the five molecules are almost equivalent [Eu(A)-O(A) 2.358 Å, Eu(B)-O(B) 2.354 Å, Eu(C)-O(C) 2.357 Å, Eu(D)-O(D) 2.357 Å and Eu(E)-O(E) 2.347 Å]; these bond distances are similar to the average Eu-O bond distances of 2.354 Å in tris(dibenzoylmethanido)(o-phenanthroline)europium(III) acetone solvate, [Eu(DBM)3(Phen)]·O(CH3)2 (Jian et al., 1989[Jian, Y., Xian, H., Zhong-Yuan, Z. & Li, L. (1989). J. Struct. Chem. 8, 187-191.]), and 2.359 Å in tris(acetylacetone)-o-phenanthroline, [Eu(acac)3(Phen)] (Watson et al., 1972[Watson, W. H., Williams, R. J. & Stemple, N. R. (1972). J. Inorg. Nucl. Chem. 34, 501-508.]). The average Eu-N bond distance of 2.641 Å is comparable with the average Eu-N bond distance of 2.642 Å observed in [Eu(DBM)3(Phen)]·O(CH3)2 (Jian et al., 1989[Jian, Y., Xian, H., Zhong-Yuan, Z. & Li, L. (1989). J. Struct. Chem. 8, 187-191.]). In the asymmetric unit, the molecules are held together by a number of weak C-H...O contacts (Table 2[link]).

[Figure 1]
Figure 1
Absorption and emission spectra of complex (I[link]): (...) absorption and emission in thf at room temperature and (-) absorption and emission in film.
[Figure 2]
Figure 2
The asymmetric unit for complex (I[link]), showing all five crystallographically independent molecules, excluding H atoms.
[Figure 3]
Figure 3
Representation of complex (I[link]), with 30% probability displacement ellipsoids, for one of five crystallographically independent molecules. H atoms have been excluded for clarity.

Experimental

The hydrated complex [Eu(DBM)3(Phen)]·xH2O, was prepared by the method of Melby et al. (1964[Melby, L. R., Rose, N. J., Abramson, E. & Caris, J. C. (1964). J. Am. Chem. Soc. 86, 5117-5125.]). The hydrated complex was transferred to a sublimation tube and heated to 433 K in vacuo, when all the water was driven off and the complex began to melt without decomposition. The temperature was raised to 453 K over a period of 12 h to melt the entire complex. The apparatus was cooled, and the molten product was dissolved in dichloromethane. After the solvent evaporated, the solid was washed five times with ethanol and dried under vacuum at room temperature for 12 h to give pure anhydrous [Eu(DBM)3(Phen)]. Orange crystals of (I[link]) were grown from an ethanol and dichloromethane solvent mixture by slow evaporation at room temperature. The purity of complex (I[link]) was verified by elemental analysis: calculated for C57H41EuN2O6: C 68.30, H 4.10, N 2.80%; found: C 68.12, H 3.8, N 2.6% (m.p. 459-461 K). IR (neat) cm-1: 1596, 1550, 1456, 724; 1H NMR (CDCl3): [delta] 6.59-8.00 (m, C6H5, 30 H), 8.92 (s, CH=, 2H), 10.01 (s, CH=, 2H), 10.52 (s, CH=, 2H), 10.92 (s, CH=, 2H), 16.89 (s, CH, 1H); 13C NMR (CDCl3): [delta] 109.7, 123.2-130.7, 131.9, 132.5, 135.5, 150.2, 168.5, 172.8, 180.5, 185.7.

Crystal data

  • [Eu(C15H11O2)3(C12H8N2)]

  • Mr = 1001.88

  • Triclinic, [P\overline 1]

  • a = 16.275 (6) Å

  • b = 23.504 (9) Å

  • c = 31.712 (12) Å

  • [alpha] = 103.844 (6)°

  • [beta] = 91.466 (6)°

  • [gamma] = 101.585 (6)°

  • V = 11504 (7) Å3

  • Z = 10

  • Dx = 1.446 Mg m-3

  • Mo K[alpha] radiation

  • Cell parameters from 1016 reflections

  • [theta] = 4.4-54.8°

  • [mu] = 1.42 mm-1

  • T = 153 (2) K

  • Parallelepiped, yellow

  • 0.24 × 0.15 × 0.10 mm
Data collection

  • Bruker SMART CCD area-detector diffractometer

  • [varphi] and [omega] scans

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2000[Sheldrick, G. M. (2000). SADABS. Version 2.03. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.776, Tmax = 0.868

  • 102 650 measured reflections

  • 49 686 independent reflections

  • 32 004 reflections with I > 2[sigma](I)

  • Rint = 0.061

  • [theta]max = 27.0°

  • h = -20 [rightwards arrow] 20

  • k = -30 [rightwards arrow] 29

  • l = -36 [rightwards arrow] 40
Refinement

  • Refinement on F2

  • R[F2 > 2[sigma](F2)] = 0.050

  • wR(F2) = 0.095

  • S = 0.99

  • 49 686 reflections

  • 2972 parameters

  • H-atom parameters constrained

  • w = 1/[[sigma]2(Fo2) + (0.0222P)2] where P = (Fo2 + 2Fc2)/3

  • ([Delta]/[sigma])max = 0.012

  • [Delta][rho]max = 0.61 e Å-3

  • [Delta][rho]min = -0.68 e Å-3

  • Extinction correction: SHELXTL

  • Extinction coefficient: 0.000029 (6)

Table 1
Selected geometric parameters (Å, °)

Eu1A-O4A 2.312 (3)
Eu1A-O3A 2.339 (3)
Eu1A-O1A 2.351 (3)
Eu1A-O6A 2.354 (3)
Eu1A-O2A 2.382 (3)
Eu1A-O5A 2.413 (3)
Eu1A-N1A 2.651 (4)
Eu1A-N2A 2.661 (4)
O1A-C13A 1.267 (5)
O2A-C15A 1.272 (5)
O3A-C28A 1.291 (5)
O4A-C30A 1.272 (5)
O5A-C43A 1.272 (5)
O6A-C45A 1.278 (5)
C13A-C14A 1.408 (6)
C13A-C16A 1.513 (6)
C14A-C15A 1.401 (6)
C15A-C22A 1.506 (6)
C28A-C29A 1.385 (6)
C28A-C31A 1.498 (6)
C29A-C30A 1.406 (6)
C30A-C37A 1.503 (6)
C43A-C44A 1.406 (6)
C43A-C46A 1.483 (6)
C44A-C45A 1.398 (6)
C45A-C52A 1.494 (6)
O4A-Eu1A-O3A 71.83 (10)
O4A-Eu1A-O1A 145.26 (11)
O3A-Eu1A-O1A 142.83 (10)
O4A-Eu1A-O6A 102.09 (10)
O3A-Eu1A-O6A 75.14 (10)
O1A-Eu1A-O6A 92.87 (10)
O4A-Eu1A-O2A 139.52 (10)
O3A-Eu1A-O2A 74.83 (10)
O1A-Eu1A-O2A 70.21 (10)
O6A-Eu1A-O2A 90.76 (10)
O4A-Eu1A-O5A 81.57 (10)
O3A-Eu1A-O5A 131.45 (11)
O1A-Eu1A-O5A 73.60 (10)
O6A-Eu1A-O5A 71.68 (11)
O2A-Eu1A-O5A 138.69 (9)
O4A-Eu1A-N1A 79.84 (11)
O3A-Eu1A-N1A 76.26 (11)
O1A-Eu1A-N1A 102.90 (11)
O6A-Eu1A-N1A 149.03 (12)
O2A-Eu1A-N1A 70.40 (10)
O5A-Eu1A-N1A 138.23 (11)
O4A-Eu1A-N2A 73.72 (11)
O3A-Eu1A-N2A 129.17 (10)
O1A-Eu1A-N2A 77.34 (11)
O6A-Eu1A-N2A 148.95 (12)
O2A-Eu1A-N2A 112.64 (12)
O5A-Eu1A-N2A 77.29 (12)
N1A-Eu1A-N2A 61.69 (12)
C13A-O1A-Eu1A 137.8 (3)
C15A-O2A-Eu1A 137.9 (3)
C28A-O3A-Eu1A 135.3 (3)
C30A-O4A-Eu1A 136.8 (3)
C43A-O5A-Eu1A 135.9 (3)
C45A-O6A-Eu1A 137.4 (3)
O1A-C13A-C14A 123.9 (4)
O1A-C13A-C16A 115.0 (4)
C14A-C13A-C16A 121.1 (4)
C15A-C14A-C13A 123.5 (4)
O2A-C15A-C14A 123.7 (4)
O2A-C15A-C22A 116.5 (4)
C14A-C15A-C22A 119.8 (4)
O3A-C28A-C29A 123.6 (4)
O3A-C28A-C31A 114.9 (4)
C29A-C28A-C31A 121.4 (4)
C28A-C29A-C30A 124.2 (4)
O4A-C30A-C29A 123.8 (4)
O4A-C30A-C37A 115.4 (4)
C29A-C30A-C37A 120.8 (4)
O5A-C43A-C44A 124.3 (4)
O5A-C43A-C46A 118.4 (4)
C44A-C43A-C46A 117.3 (4)
C45A-C44A-C43A 125.0 (4)
O6A-C45A-C44A 124.5 (4)
O6A-C45A-C52A 116.4 (4)
C44A-C45A-C52A 119.0 (4)
C43B-C44B-C45B 123.5 (4)

Table 2
Hydrogen-bonding geometry (Å, °)

D-H...A D-H H...A D...A D-H...A
C1A-H1AA...O3A 0.95 2.54 3.119 (6) 120
C10A-H10A...O5A 0.95 2.40 3.094 (8) 129
C10B-H10B...O5B 0.95 2.44 2.997 (6) 118
C10C-H10C...O3C 0.95 2.38 3.016 (6) 124
C10D-H10D...O3D 0.95 2.42 3.017 (6) 121
C10E-H10E...O3E 0.95 2.51 3.153 (6) 125
C17A-H17A...O1A 0.95 2.38 2.716 (6) 100
C32B-H32B...O3B 0.95 2.40 2.736 (7) 100
C47C-H47C...O5C 0.95 2.36 2.702 (6) 100
C47E-H47E...O5E 0.95 2.32 2.679 (6) 101
C53E-H53E...O6E 0.95 2.36 2.692 (6) 100
C57C-H57C...O6C 0.95 2.40 2.730 (7) 100

All H atoms were placed geometrically and refined using a riding model with Uiso(H) = 1.2Ueq(C) and C-H = 0.95 Å. Atoms C55C and C56C have slightly large displacement parameters. A disorder model with two orientations for the phenyl ring did not improve the refinement.

Data collection: SMART (Bruker, 2000[Bruker (2000). SMART (Release 5.611) and SAINT (Release 6.02a). Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2000[Bruker (2000). SMART (Release 5.611) and SAINT (Release 6.02a). Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1998[Sheldrick, G. M. (1998). SHELXTL. Version 5.1. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Acknowledgements

The authors thank the National Science Council and the Ministry of Education for financial support through project 91E-FA04-2-4A of the Republic of China. JHK thanks the Province of Ontario and the Natural Sciences and Engineering Research Council of Canada (NSERC) for graduate fellowships.

References

Balzani, V. (1992). Tetrahedron, 48, 10443-10514. [CrossRef] [ChemPort]
Bhaumik, M. (1965). J. Chem. Phys. 42, 787-788.  [CrossRef] [ChemPort]
Briggs, J. (1970). Chem. Commun. pp. 749-750.
Bruker (2000). SMART (Release 5.611) and SAINT (Release 6.02a). Bruker AXS Inc., Madison, Wisconsin, USA.
Crosby, G. A. & Whan, R. E. (1960). J. Chem. Phys. 32, 614-615.  [CrossRef] [ChemPort]
Edwards, A., Claude, C., Sokolik, I., Chu, T. Y., Okamoto, Y. & Dorsinvill, R. (1997). J. Appl. Phys. 82, 1841-1846. [CrossRef] [ChemPort]
Halverson, F., Brinen, J. S. R. & Leto, J. (1964). J. Chem. Phys. 40, 2790-2792.  [CrossRef] [ChemPort]
Hinckley, C. C. (1969). J. Am. Chem. Soc. 91, 5160-5162. [CrossRef] [ChemPort] [PubMed]
Jian, Y., Xian, H., Zhong-Yuan, Z. & Li, L. (1989). J. Struct. Chem. 8, 187-191.
Kido, J., Hayase, H., Hongawa, K., Nagai, K. & Okuyama, K. (1994). Appl. Phys Lett. 65, 2124-2126. [CrossRef] [ChemPort]
Mazdiyasni, K. S., Lynch, C. T. & Smith, J. S. (1966). Inorg. Chem. 3, 342-346.  [CrossRef]
Melby, L. R., Rose, N. J., Abramson, E. & Caris, J. C. (1964). J. Am. Chem. Soc. 86, 5117-5125. [CrossRef] [ChemPort]
Qian, D. J, Yang, K. Z, Nakahara, H. & Fukuda, K. (1997). Langmuir, 13, 5925-5932. [CrossRef] [ChemPort]
Pope, G. W., Steinbach, J. F. & Wagner, W. F. (1961). J. Inorg. Nucl. Chem. 20, 304-313.  [CrossRef] [ChemPort]
Sano, T., Fujita, M., Fujii, T., Hamada, Y., Shibat, K. A. & Kuroki, K. (1995). Jpn. J. Appl. Phys. 34, 1883-1886. [CrossRef] [ChemPort]
Sheldrick, G. M. (2000). SADABS. Version 2.03. Bruker AXS Inc., Madison, Wisconsin, USA.
Sheldrick, G. M. (1998). SHELXTL. Version 5.1. Bruker AXS Inc., Madison, Wisconsin, USA.
Uekawa, M., Miyamoto, Y., Ikeda, H., Kaifu, K. & Nakaya, T. (1998). Bull. Chem. Soc. Jpn, 71, 2253-2258.  [CrossRef] [ChemPort]
Watson, W. H., Williams, R. J. & Stemple, N. R. (1972). J. Inorg. Nucl. Chem. 34, 501-508. [CrossRef] [ChemPort]
Whan, R. E. & Crosby, G. A. (1962). J. Mol. Spectrosc. 8, 315-327.  [CrossRef] [ChemPort]

Acta Cryst (2003). E59, m29-m32   [ doi:10.1107/S1600536802023036 ]